The resolution issue field represents how an issue was resolved.
You can define the available resolutions by going to General - Settings - Issue configuration - Issue resolutions. Here you can add, rename and remove the resolutions.
The ones initially available are:
- Fixed - the issue has been fixed and completed.
- Workaround - The issue is completed but not fixed, but you can use a work around the problem.
- Rejected - The issue will not be fixed, probably because it is not really a problem to start with.
- Duplicate - This issue is completed as a duplicate, and the real resolution is in the original issue.
- Cannot reproduce - The issue is completed as you cannot reproduce the problem.